“…Plasma electrolytic oxidation (PEO), so called micro-arc oxidation (MAO), is a relatively convenient technique to deposit ceramic coatings on titanium substrate, and PEO has drawn widely attentions due to the porous, nanostructured and firmly adhered coating characteristics [17][18][19][20]. It is an effective and simple way to prepare various functional composite coatings using PEO technology by tailoring the electrolyte compositions and controlling process parameters, and several kinds of composite coatings (such as TiO 2 /HA, TiO 2 /Al 2 O 3 and MgO/ZrO 2 ) have been prepared in recent few years [21][22][23].…”